~ 
336 LXXV. COMPOSITE. PARTHENIUM. 
2-toothed pappus.—% Stout, coarse, resinous herbs. Has. large. Fis. 
yellow. 
1. S. Lacinritum. Rosin-weed. Polar Plant. 
Very rough, with white, hispid hairs; dvs. alternate, pinnately parted, 
lower petiolate, segments sinuate-lobed or entire; ids. spicate, distant; scales 
of involucre ovate, appendaged and squarrose at apex.—Western States! to 
Tex., producing columns of smoke in the burning prairies by its copious resin. 
Stem 3—10f high. Lower leaves 1—2f long, much divided, resembling those 
of some thistles. Heads 4—8, very large, with large, yellow rays. Jl—Sept. 
2. S. TEREBINTHINACEUM. Prairie Burdock. 
S¢. and ped. glabrous; lvs. mostly radical, ovate and ovate-oblong, cor- 
date, dentate-serrate, obtuse, scabrous, on long petioles; hds. few, paniculate ; 
scales roundish and oval, glabrous.—Prairies, Western! and Southern States. 
Plant exuding resin. Stem 4—8f high, nearly naked and simple. Leaves 
erect, scabrous, rigid, 1—2f long, 7—16’ wide. Involucre globose. Rays 15— 
25, 1’ long. Achenia narrowly 2-winged. July—Sept. 
B. pinnatifidum. T. & G. (S. pinnatifidum. Ell.) JLws. more or less deeply 
lobed or pinnatifid. 
3. S. TRIFOLIATUM. Ternate-leaved Silphiwm. 
St. glabrous and often glaucous, terete or 6-sided ; cauline lwvs. lanceolate, 
acute, scabrous above, smooth below, remotely dentate, on very short petioles, 
verticillate in 3s or 48; wpper ones opposite; Ads. loosely eymose, on rather 
long peduncles; scales broadly ovate, rather obtuse, smooth; ach. oval, with 2 
short teeth—Dry woods and prairies, Ohio, Sullivant! and Southern States. 
Stem 4—6f high —Leaves 4—6’ by 1—2””.. Rays 12—16, expanding about 23’. 
4. S. inrecrirotium. Michx. 
Scabrous; st. quadrangular, striate, simple; dvs. opposite, sessile, ovate- 
lanceolate, entire or slightly dentate; Ads. in a close corymb; scales squarrose ; 
ach. roundish, broadly winged, with 2 long teeth—Western States! 8. to Ga. 
Stem very rigid, 3—7f high. Leaves rigid, broad and clasping at base, 3—6’ 
long, 3} as wide, rather variable in form. Heads middle-size. Rays 12—20, 1’ 
in length. Achenia twice as large as in the preceding species. July, Aug. 
B. ternatum. Wood. St. 6-sided; lvs. ternately verticillate-——Prairies! with 
the common form; apparently connecting this with 8. trifoliatum, from which 
it is nevertheless quite distinct in habit. 
5. S. PERFOLIATUM (and S. connatum. Linn.) Cup-plant. — 
St. square; lvs. large, thin, opposite, connate-perfoliate, ovate, Coarsely 
toothed, narrowed towards the base; Ads. in a trichotomous cyme, the central 
on a long peduncle ; scales ovate, obtuse, squarrose ; ach. broadly obovate, winged, 
emarginate.—Along streams, &c., Mich.! to Tenn. A coarse, unattractive 
plant, quite distinct, although variable. Stem 4—7f high. Leaves 8—14’ by 
4—7', the upper pairs forming a cup with their connate bases. Heads large, 
with 15—25 ravs. 
28. PARTHENIUM. 
Gr. rapSevos, a virgin; from its medicinal efficacy. 
Heads many-flowered ; ray-flowers 5, somewhat ligulate, fertile ; 
disk-flowers tubular, sterile: involucre hemispherical; scales in 2 
series, outer ovate, inner orbicular ; receptacle conical, chaffy; ache- 
nia 5, compressed, cohering with 2 contiguous paleze—American herbs 
with alternate leaves. 
P. INTEGRIFOLIUM- 
St. pubescent, striate, erect; vs. hispid-scabrous, lance-ovate, coarsely 
dentate-crenate, coriaceous, lower petiolate, upper sessile; Ads. many, tomen- 
tose, corymbed—1| Dry soiis, Middle and Western States! Stem rigid, 3—5f 
high. Radical petioles 1f long. Leayes 4—12’ long, as wide. Heads white, 
with 5 very short, cucullate, white rays, July—Sept. 
